Study Guide
Phases of a Thunderstorms Life Cycle
Thunderstorms, characterized by towering cumulonimbus clouds, can develop rapidly and unpredictably, presenting dangers that range from severe turbulence to lightning strikes. The average thunderstorm has a 24 km (15 mi) diameter.
The three phases of thunderstorms:
- cumulus
- mature
- dissipating
Thunderstorms occur in a type of cloud known as a cumulonimbus.
During this stage, masses of moisture are lifted upwards into the atmosphere.
This phase features vigorous updrafts and the developing cumulus clouds, signify the initial phase of a thunderstorm’s life cycle.
The start of rain from the base of the cloud signals the beginning of the mature stage.
The air is instead forced to spread out, giving the storm a characteristic anvil shape.
This stage is when the storm reaches its peak intensity with powerful updrafts and downdrafts, accompanied by precipitation and potential severe weather phenomena.
“As the cumulus cloud continues to grow, the tiny water droplets within it grow too because as they’re flying up there in the cloud, they’re colliding and sticking to each other. This is when the cloud starts looking dark and gray. Raindrops start to fall through the cloud when the rising air can no longer hold all those water droplets up. Meanwhile, cool dry air flows downward in the cloud (the downdraft), pulling water downward as rain. With an updraft, downdraft, and rain, the cloud is now called a cumulonimbus cloud and the cycling of air up and down is called a thunderstorm cell.” – CNY
During the Dissipating Stage (Stage 3) of a thunderstorm, the weakening storm forms an anvil-shaped cloud as downdrafts increase and updrafts cease, marking the concluding phase of the thunderstorm’s life cycle.
“When the downdrafts in the cloud become stronger, they eventually start cutting off the updraft. This leads to the last stage of a thunderstorm where it weakens and dissipates. The storm dies out with light rain as the cloud disappears from bottom to top. The whole process takes about one hour for an ordinary thunderstorm. Severe thunderstorms like supercells and squall lines are much larger, more powerful, and last for several hours.” – CNY
3 Conditions Needed for Thunderstorms
Let’s explore the practical implications of having sufficient water vapor, an unstable lapse rate, and an initial lifting force. This knowledge is crucial for drone operators to assess weather conditions effectively.
Water in the Air: There needs to enough water vapor moisture in the air. (This is why thunderstorms frequently occur when the humidity level is high.)
Building Blocks for Clouds: This water vapor provides the building blocks needed to create clouds and precipitation in the form of rain or storms.
The unstable air in the atmosphere, caused by this rapid temperature decrease, causes the vertical movement of air. Unstable conditions mean that as you go higher in the sky, the air gets colder quickly. This rapid cooling lets warm air near the ground rise easily, which starts the process of making big thunderstorm clouds called cumulonimbus clouds.
This upward motion is like the initial spark that sets off the chain reaction leading to the development of thunderstorms. Thunderstorms result from the rapid upward movement of warm, moist air. It requires:
Something to Lift the Air: There needs to be a force, like a front (meeting of air masses), a mountain, or the rising lift of hot air rising from the ground.
Trigger for Upward Motion: This force acts as a trigger, lifting the warm, moist air, starting the process that leads to the development of thunderstorms.
SIGMENTS
SIGMETs deliver vital weather advisories during flights, offering essential information that enhances flight safety. They are among the best resources for understanding and preparing for adverse weather conditions along your route.
- Surface winds gusting at 45 knots or above.
- Hail measuring 1 inch in diameter or larger.
- Tornado occurrences.
- Embedded, line, or area thunderstorms.
- Severe thunderstorms rated at VIP level 5 or higher that affect 50% or more of an area of at least 4,000 square miles.
Cumulonimbus Clouds of Thunderstorms
Hazards Related to Thunderstorms
- Lighting:
- Consistently associated with thunderstorms because it results from the buildup and discharge of electrical energy within the storm clouds.
- Lightning is the most hazardous circumstance when operating an sUAS in close proximity to thunderstorms.
- Hail
- Thunderstorms can also bring hail, which can hit areas far from the storm, including where you’re flying your drone. Don’t assume you’re safe just because the storm seems far away—hail, even small pieces, can mess up your drone.
- Turbulence
- Thunderstorms are notorious for generating severe turbulence, especially in their mature stage. The intense updrafts and downdrafts within this stage can create sudden and strong changes in air movement.
- Icing
- Thunderstorms at high altitudes create supercooled water droplets that freeze on aircraft surfaces. Icing on drones increases weight, disrupts aerodynamics, reduces lift, and can lead to loss of control.
- Microbursts
- Thunderstorms can create microbursts, which are sudden, strong winds that blow downward. Microbursts can cause planes to drop quickly and are very dangerous during takeoff or landing.
- Windshear
- Thunderstorms cause windshear, a sudden change in wind direction and speed.
- Squall Lines
- A squall line is a long, narrow line of intense thunderstorms that can bring strong winds, heavy rain, hail, and sometimes tornadoes.
- Tornados
- Tornadoes can potentially develop from any cloud linked to a severe thunderstorm, even if it’s many miles from the main thunderstorm cloud.
Quick Review
Vigorous Updrafts
are part of which thunderstorm stage?Cumulus Stage
Stage 1Peak Intensity
are part of which thunderstorm stage?Mature Stage
Stage 2Anvil-shaped Cloud
are part of which thunderstorm stage?Dissipating Stage
Stage 3
Powerful Updrafts & Downdrafts
are part of which thunderstorm stage?Mature Stage
Stage 2 (accompanied by precipitation)
Cumulonimbus Clouds
are part of which thunderstorm stage?Cumulus Stage
Stage 1
Downdrafts Increase & Updrafts Cease
are part of which thunderstorm stage?Dissipating Stage
Stage 3
Rain Starts
are part of which thunderstorm stage?Mature Stage
Stage 2 (start of rain signals start of mature stage)
Weakening Storm
are part of which thunderstorm stage?Dissipating Stage
Stage 3 (marking the concluding phase of the thunderstorm’s life cycle)
